1. Field of the Invention
The present invention relates to a method for high resolution patterning and a process for manufacturing a nano device using the high resolution pattern, and more particularly, to a method for micro- or nano-scale high resolution patterning within a short period of time, and a nano device formed using the method.
2. Description of the Related Art
With recent advances in the semiconductor industry and the need for highly-integrated semiconductor devices, nano- or micro-fabrication technologies for minute patterning attract more and more attention.
As is expected by many experts that nanotechnology will be one of the leading technologies in the 21st century, nano-pattern fabrication is an essential technology of the highest priority in minute-circuit processing for large-capacity semiconductor devices. In addition, nano-patterning technology has wide applications, for example, in the bioengineering related field and for biosensors, so its consequence becomes great.
So far, surface patterning has been achieved by photolithography employing deep UV radiation and polymer-photoresists, leading to stunning advances in the semiconductor industry for the last decade.
Pattern resolution in photolithography is determined according to Rayleigh's equation, R=k1 λ/NA, where R denotes resolution, λ denotes wavelength, k1 is a constant, and NA denotes the numerical aperture of a lens system. A shorter wavelength of light used results in higher resolution and smaller patterns. A pattern resolution on the order of 500 nm, achieved in the early 1980s by G-line (436 nm) exposure systems using high-pressure mercury lamps, has markedly been reduced to 180 nm recently by the use of 248-nm KrF eximer laser exposure technology, thereby realizing the production of 1-Gb memory semiconductors (Solid State Technol., January 2000). However, due to the limitations in the wavelength of usable light, equipment and technology requirements, and the resolution of polymeric photoresist used, it is difficult to form nano-scale high-resolution patterns with this method.
For higher pattern resolutions, many attempts have been made since 1990, for example, using self-assembled monolayers as a new photoresist, instead of polymers used in conventional photolithography, and using light of a short wavelength. In addition, new patterning technologies for self-assembled monolayers, for example, soft lithography or scanning probe lithography using tips of AFM and STM have been introduced.
In the early 1990s, Whitesides, a professor at Harvard University, termed surface patterning using an elastomeric stamp or mold to ink a solid substrate with the help of molecular self-assembly, not using light or high energy particles, as “soft lithography” and reported many research results (Appl. Phys. Lett., 1993, 63, 2002). A representative example is concerned with microcontact printing (μCP) involving stamping surfactant molecules, for example, alkanethiol, in a surface area with a polydimethylsiloxane (PDMS) elastomer stamp to form patterns of self-assembled monolayers only on the stamping area. This microcontact printing enables speedy and economical consecutive patternings. However, this technique has some problems to be solved, such as inaccurate registration (<1 μm) due to the deformation of an elastomeric stamp, incompatibility with current integrated circuit (IC) processes, etc.
Recently, Mirkin et al. have developed “dip-pen” nanolithography (DPN) which uses an AFM tip as a “nib”, a solid substrate (for example, Au) as “paper”, and molecules with a chemical affinity for the solid substrate as “ink”. Molecules are delivered from the AFM tip to a solid substrate of interest via capillary transport (Science, 1999, 283, 661). Due to the use of elaborately formed sharp tips, dip-pen nanolithography offers a high-resolution, nano-scale pattern of about 5 nm. However, its time-consuming serial pattern drawing processes limit commercialization through mass production.